Process of recovering escaping acid-gases from sulfite-towers.



"J.A.DEGEW. PROCESS OF REGOVERING ESGAPIHG AGID GASES'FROM SULFITB TOWERS.

APPLICATION FILED N0\T.13, 1911.

Patented Oct. 28,1913.

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7 intervals with furous acid of the city of Montreal, in the Province of Quebec and D .fite liquor for pulp making.

JULDSON A. DE cnw, or MONTREAL, QUEBEC, CANADA PROCESS OF RECOVERING ESGAPING ACID-GASES FROM SULFITE-TOW'ERS.

Specification of Letters Patent.

Patented oc e. as, rare; Serial No. 659,944. i

Application filed November 13, 1911.

To all? whom z'l may concern.

Be it known that I, J UDSON A. DE Cnw,

ominion of Canada, have invented certain new and useful Improvements in Processes; of Recovering Escaping Acid-Gases from Sulfite-Towers, and do hereby declare that the following is a full, clear, and exact description of the same.

This invention relates to a process of recovering eseeping acid gases from the sulfit-e towers used in the manufacture of sulln,the manufacture of sulfite pulp, the liquor is usually prepared in towers, or their equivalent, packed with limestone by forcinggas from a sulfite burner up through the limestone while a stream of water passes down. The Water and sulfur gas combine and form sulfurous acid which in turn attacks the limestone and produces the sulfite liquor. Ordinarily, the sulfur gas is eomposed of from 12% to 17% sulfur dioxid, by volume, the balance being mostly nitrogen, and this gas leaves the tower containing from 1% to 2% sulfur dioxid. Therefore, if no gas leaks out of the towers the loss is about 10% of the amountentering. In many'towers, however, provided with exhaust fans, the loss amounts to from 15% to 20%. In order to overcome this loss, I pass the gas through moistened stones of mag The apparatus for carrying out this recovery process is illustrated in the accompanying drawing.

Referring to the drawing, 1 tower of suitable dimensions provided at horizontal apertured diaphragms 2 which divide the tower in chambers 3, 4 and 5. The chamber 3 at the bottom of the tower is provided with a gas inlet I pipe 6 from a sulfur burner and'with an outlet pipe '1' for the sulfite liquor. The chambersl are for the reception of limestone (CaCO 8 von whiclnthe water and sulacts. The upperchambero condesignates a which wouldbe tains calcined magnesia 9 and is provided with a gas outlet; pipe 10 and a water inlet pipe .11. The chambers 4- and 5 are provided at the top with suitable charging. apertures 12 closed by doors 13'. Adjacent the doors are loading floors or platforms let. The operation is as follows z-Sulfur dioxid (S0 is supplied through'the pipe 6, andris'es through the limestone whichis kept wet with water from the pipe 11. The water and sulfur dioxid'combine and form sulfurous acid which attacks the limestone,

', the product being the sulfite liquor which falls into the chamber 3 and is drawn o f through the pipe 7. The nitrogen which cn ters with the sulfur dloxld andalso other gas vliberated by the chemical through the follows H 0 and SO =H SO H 30 and 0300 50380 and H 0 and CO H 80 and CaSO L-CaH (S0 In the. second line of the'reaetion where the' CO in the stone is replaced by SO in the acid the rate of the action depends on the strength of the acid. Therefore toi'vard the top of the tower the stone is'.very slowly pipe 10. The reaction is as age of unabsorbed ditional chamber nesia preferably 1n lump form prevents this gas which is lost. The adloss. The magnesia does not slack like lime sulfur dioXid much than ,limestone. The acid too Weak to attack limestone is absorbed by the magnesia cred as magnesium sulfite and bisulfite. The apparatus need not tower but may be a. series and also absorbs the more readily.

of intercommuniaction escape 5 containing calcined mag and 1S recovnecessarily be a eating vessels arranged in a train, the final I 1 vessel of the train being charged; with calcined magnesia.

Having now I declare that what I claim 1s:-

1-. A process of recovering escaping acid fully described my invention,

75 attacked because the acidity of the water- 1s so slight. There ls-also a small percentgas in the nmnufacture of sulfite liquor limestone and moistened calcined magne- 16 which consists in passing the escaping gas site in lump form.

through chambers contalning moistened In witness whereof I have hereunto set limestone and then through a chamber conmy hand in the presence of two witnesses.

5 taining moistened calcined Ina esite. I

2. A process of recovering egd epinggas in JUDSON E the manufacture of sulfite hquor which con-, Witnesses: sists in passing the escaping gas successively STUART R. N. ALLEN, through chambers containing moistened G. M. MORELAND.

v M Gop'iea of this patent may be obtained for five cents each, by addressing the Commissioner of Iatents.

. Washington, D. (2.: 

